Phosphate additives in a tar sand water separation process



Jan. 14, 1969 J. A. BICHARD 3,422,000

PHOSPHATE ADDITIVES IN A TAR SAND WATER SEPARATION PROCESS Filed Nov. 18, 1965 l5 L TAR SAND M 40 I IO r 6O 7 FROTH- DILUENT 3O SAND MM 4. Maw/1v mvsmon PATENT ATTORNEY United States Patent 3,422,000 PHOSPHATE ADDITIVES IN A TAR SAND WATER SEPARATION PROCESS John A. Bichard, Point Edward, Ontario, Canada, as-

signor to Esso Research and Engineering Company, a

corporation of Delaware Filed Nov. 18, 1965, Ser. No. 508,439

US. Cl. 20811 Int. Cl. C10g N00 5 Claims ABSTRACT OF THE DISCLOSURE The present invention is broadly concerned with the recovery of hydrocarbons from tar sands. The invention is more particularly concerned with an improved technique for the maximum removal of oil from tar sand utilizing a particular combination of phosphate additives. In accordance with the present invention by utilizing critical amounts of particular phosphate additives, a maximum amount of oil is removed from the sand which is associ ated with the froth separated from the treated sand.

In various areas of the world, tar sands exist which contain various types of hydrocarbons as, for example, the heavy oil deposits of Athabaska tar sands existing in Canada. These sands constitute tremendous reserves of hydrocarbon constituents. For example, the oil in the sands may vary from about 5% to 21% by volume, generally in the range of about 12% by volume. The gravity of the oil ranges from about 6 to 10 API, generally about 8 API. These sands lie from about 200 to 300 ft. below an overburden and the beds may range from about 100 to 400 ft. thick. A typical oil recovered from the sands has an initial boiling point of about 300 F. 1.0% distilled to 430 F., 20.0% distilled to 650 F. and 50.0% distilled to 980 F.

However, the recovery of hydrocarbons in the past has not been effective to any great extent due to the deficiencies in operating techniques for the recovery of these hydrocarbons. For example, a relatively small amount of clay (from about 0% to 30%, usually 5%) in the sand greatly retards recovery of the oil utilizing conventional water techniques. Apparently the oil and the clay form skins which envelop small pockets of water often containing finely divided sand; then the enveloped pockets are distributed in water, thus forming a type of emulsion. Since large amounts of material must be treated and handled to recover the oil, any technique or process which improves the yield of oil even slightly will result in great economic benefits.

In accordance with the present invention, a particular class of sodium phosphate compounds is used wherein the sodium concentration is maintained in a critical range from about 0.4 wt. percent to about 0.8 wt. percent preferably about 0.4 to 0.6 wt. percent, such as about 0.5 wt. percent, as compared with the sand in an initial stage wherein the amount of water utilized is in the range from about to 30% by weight based upon the sand. The preferred amount of water is from about 18% to 26% by weight, preferably about 22% by weight. The phos- 3,422,000 Patented Jan. 14, 1969 phate compound utilized is selected from the class of sodium phosphate compounds wherein the ratio of phosphorous to sodium varies from about 1:1 to 1:2, preferably about 121.7.

The process of the present invention may be readily understood by reference to the drawing illustrating an embodiment of the same. Referring specifically to the drawing, tar sands are introduced into initial stage 10 by means of feed line 1. Water is introduced into initial stage or mixing zone 10 by means of line 2. The amount of water utilized in initial stage 10 based upon the sand is in the range from about 15 to 30% preferably in the range of about 20 to 22% by weight.

Initial stage 10 is maintained at a temperature in the range from about 120 to 200 F., preferably at about 140 F., by any suitable means. In accordance with the present invention, a sodium polyphosphate compound is introduced into initial stage 10 by means of line 3. The amount of sodium polyphosphate utilized is such as to secure a sodium concentration based upon the amount of sand in the range from about 0.4 to 0.8 wt. percent, preferably about 0.5 wt. percent. The sodium polyphosphate compound utilized is selected from the class of compounds wherein the phosphorous-to-sodium ratio is in the range from about 1:1 to 1:2, preferably about 111.7. Any suitable means of mixing may be utilized in zone 10 such as stirrers and the like.

The mixture is withdrawn from initial zone 10 by means of line 4 and mixed with additional water which is introduced by means of line 5. The amount of additional water utilized is sufiicient to have from about -300% by weight of water, preferably about 200% by weight of water based upon the sand. The mixture is then introduced into a secondary stage or separation zone 20.

The temperature in secondary stage 20 is in the range of from about to 200 F., preferably about F. Under these conditions sand and water substantially free of oil, is removed from secondary stage 20 by means of line 6 while an aqueous froth containing substantially all of the oil and a relatively small quantity of water is removed from zone 20 by means of line 7. The Water phase and and removed by means of line 6 is passed into a sand separation zone 30 wherein a water phase free of sand is separated and preferably recycled to the system. Since this water phase contains the added phosphate the sand is removed from separation zone 30 by means of line 8 and disposed of as desired.

The oil-rich froth is then handled or processed in order to secure an oil phase. One preferred method is to introduce the oil froth into a distillation zone 40 in order to remove overhead water by means of line 9. It is preferred that the oil phase withdrawn from distillation zone 40 by means of line 11 be at a temperature in the range from about 250 to 400 P. such as about 300 F. A hydrocarbon diluent such as a hydrocarbon fraction boiling in the range from about 250 to 600 F. is added to the oil phase by means of line 12. Other hydrocarbons may be added such as benzene, toluene, and the like. The amount of diluent added is about 0.5 to 2.0 volumes of diluent per volume of oil. Sufficient pressure is maintained on the system to keep the diluent in the liquid phase. The mixture is then passed into a final solids separation zone 50 wherein the remaining traces of solids separate and are removed by means of line 13. Separation zone 50 may comprise filters or settling means. A diluent oil phase is removed from separation zone 50 by means of line 14 and introduced into a diluent-heavy oil separation zone 60 wherein the diluent is separated and removed by means of line 15 and preferably recycled to the system. The heavy oil phase is removed by means of line 16 and further processed as desired. Sepa- OIL REC. IN FROTH, WT. PERCENT Na con. wt. percent (based on tar sand) P/Na 0 From the above it is apparent that the oil froth contained a far greater concentration of oil when utilizing a sodium concentration in the range from about 0.4 to 0.8, and when using a phosphorous-to-sodium ratio as defined by the present invention.

What is claimed is:

1. Improved process for the recovery of oil from tar sands which comprises mixing said tar sand with from about wt. percent to 30 wt. percent of water in an initial mixing zone maintained at a temperature of about 120 F. to 200 F., adding a sodium phosphate compound to mixing zone so as to have a sodium concentration based upon the weight of the tar sand in the range from about 0.4 to about 0.8 wt. percent and to have a phosphorous-to-sodium ratio in the range from about 1:1 to 1:2, withdrawing the mixture from said mixing zone and adding additional water so as to have a water concentration in the range from about 100% to 300% by weight based upon the tar sand, thereafter passing the mixture to a secondary zone maintained at a temperature in the range from about 120 to 200 F., removing an oil-rich froth and a sands-water phase from said secondary zone, passing said froth to a distillation zone and removing water overhead from said distillation zone, removing an oil phase from the bottom of said distillation Zone and adding a hydrocarbon diluent boiling in the range from about 250 to 600 F. thereto, passing the mixture to a tertiary zone and separating the final traces of solids therefrom, and thereafter separating said oil from said diluent.

2. Process as defined by claim 1 wherein the sodium concentration in said mixing zone is about 0.5% by weight and wherein the phosphorous-to-sodium ratio is about 1 to 1.7.

3. Process as defined by claim 1 wherein the amount of diluent added is about one volume of diluent per one volume of bottoms oil phase.

4. Process as defined by claim 1 wherein said diluent consists essentially of benzene.

5. Process as defined by claim 1 wherein from about 0.5 to 2 volumes of diluent are added per volume of oil.

References Cited UNITED STATES PATENTS 1,820,917 9/1931 Langford et a1. 208-11 2,453,060 11/1948 Bauer et a1 208-11 3,152,979 10/1964 Bichard et al. 208--11 3,208,930 9/1965 Andrassy 208-11 3,296,117 1/1967 Ross et a1. 20811 FOREIGN PATENTS 488,928 12/ 1952 Canada. 602,087 7/ 1960 Canada.

OTHER REFERENCES Canadian Chemical Processing, Sun Oil Company, August, 1964.

DANIEL E. WYMAN, Primary Examiner.

PAUL E. KONOPKA, Assistant Examiner.

US. Cl. X.R. 209166 

